Epsilon-near-zero (ENZ), or low-refractive index, metamaterials are an interesting class of structures for novel applications at optical, THz, and microwave frequencies. It is possible to improve previously well-known optical systems utilizing the properties of such artificial materials. Thus, the present disclosure incorporates an ENZ metamaterial into waveguides in order to suppress the usual dispersion associated with the interaction of light with material in the core, guiding layer of the (dielectric) waveguides.
An ideal “material” for the core is air, since it has minimum interaction with light. However, in dielectric waveguides, the core must possess a higher refractive index than the cladding, even though, for example, in telecommunication fibers, the difference is best kept very small to maintain single-mode operation. Thus, ENZ metamaterials can provide a mechanism for such air-core waveguides by the introduction of a cladding medium exhibiting a refractive index that is less than unity.